GX3146 Datasheet, PDF (29/46 Pages) Semtech Corporation – Crosspoint Switch with Trace Equalization and Output De-emphasis

Note that the values of RX0_PRBS_LOCK and RX1_PRBS_LOCK, RX0_PRBS_PASS
and RX1_PRBS_PASS, RX0_PRBS_FAIL and RX1_PRBS_FAIL,
RX0_PRBS_ERROR_COUNT and RX1_PRBS_ERROR_COUNT are reset whenever
any of the corresponding test parameters for the RX0 and RX1 pattern checkers are
updated as well as whenever the corresponding RX0_PRBS_ENABLE or
RX1_PRBS_ENABLE bits are set to '1' when previously set to '0'. To start a new PRBS test
when the previous one has already been run, either re-write
RX0_PRBS_BER_TIME/RX1_PRBS_BER_TIME or toggle
RX0_PRBS_ENABLE/RX1_PRBS_ENABLE.
Note: The pattern checkers will count zero errors if the incident data is simply a static
zero.
4.7 Horizontal Eye Measurement
As explained above, the GX3146 enables the measurement of bit error “bathtub” curves
at the video rates of 1485Mb/s and 2970Mb/s to assist in evaluating how much margin
there is in the system.
See Using the Monitoring Features of the GX3290 Application Note for more
information.
4.7.1 Configuration for Horizontal Eye Measurement
• Route the input signal of interest to the MON0 or MON1 of the matrix
• Route the monitor output of matrix to pattern checker Rx , (RX0 in the notes below)
by changing the RX0_CHECK_KEY_D2A word from its default value of 512
(decimal) to 288 (decimal)
• For a PRBS pattern, select a pattern length with a value of the
RX0_PRBS_POLYNOMIAL bits set to match the source pattern, and set the
RX0_PRBS_CHK_MODE bits to 1 to select the phase interpolator path
• For an arbitrary pattern, set the RX0_PRBS_CHK_MODE bits to 2 to select the
direct data comparison mode
• Set initial sampling phase with the
RX0_PHASE_INTERPOLATOR_PHASE_SEL_D2A bits (in the BIST_RX_4 register)
• Initiate error counting as described in Section 4.6.2 above
• Increment the sampling phase
• Count errors
• Repeat last two steps to cover one UI
4.8 Temperature Sensors
The GX3146 has twelve on-chip temperature sensors comprised of four junction diode
temperature sensors and four ADCs, each with two selectable temperature sensors.
Analog output voltages can be used to determine the temperature of the chip at the
junction diode temperature sensors in four different locations. An external test current
is applied to each sensor, and the voltage across the sensor is measured.
Note that the “A” and “K” of the pin names indicate the preferred direction of the test
current, but other junctions are present internally. Test currents should be limited to
10mA or less.
GX3146 146 x 146 3.5Gb/s Crosspoint
Final Data Sheet Rev. 2
GENDOC-056075 March 2013
www.semtech.com
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